package com.singzi.newcode.pdd;

import java.util.Scanner;
import java.lang.Math;
public class Main1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        String str1 = scanner.next();
        String str2 = scanner.next();
        int []letters1 = new int[26];
        int []letters2 = new int[26];
        for(int i = 0;i < n;i++){
            letters1[str1.charAt(i) - 'a']++;
            letters2[str2.charAt(i) - 'a']++;
        }
        int []letter1 = new int[n];
        int []letter2 = new int[n];
        int j = 0, k = 0;
        for (int i = 0; i < 26; i++) {
            while (letters1[i] > 0) {
                letter1[j] = i;
                j++;
                letters1[i]--;
            }
            while (letters2[i] > 0) {
                letter2[k] = i;
                k++;
                letters2[i]--;
            }
        }
        int sum = 0;
        for (int i = 0; i < n; i++) {
            sum += Math.abs(letter1[i] - letter2[i]);
        }
        System.out.println(sum);

    }
}
